Question

A lady has only 20-paisa coins and 25-paisa coins in her purse. If she has 50 coins in all totalling Rs 11.50, how many coins of each kind does she have?

Answer 1

Let the number of 20-paisa coins be x and that of 25-paisa coins be y.
Then, we have:
x + y = 50 ....(i)
20x + 25y = 1150 ....(ii) [Since Re. 1 = 100 paisa]
On multiplying (i) by 20, we get:
20x + 20y = 1000 ....(iii)
Subtracting (iii) from (ii), we get:
(25y − 20y) = (1150 − 1000)
⇒ 5y = 150
⇒ y = 30
On substituting y = 30 in (i), we get:
x + 30 = 50
⇒ x = (50 − 30) = 20
Hence, the number of 20-paisa coins is 20 and the number of 25-paisa coins is 30.